A conventional package-on-package (PoP) structure provides an integrated circuit die coupled to a memory device using a bottom package that contains the integrated circuit die and a top package that contains one or more memory die. FIG. 1A illustrates a prior art PoP structure 100. An integrated circuit die 110 may be mounted on top of a bottom package 125 using a flip-chip configuration so that solder balls provide a die to bottom package coupling 115. The bottom package 125 includes a bottom package coupling 112 (e.g., solder balls, bumps, dots, etc.) to couple the bottom package 125 portion of the PoP structure to a printed circuit board or other system substrate.
The bottom package 125 includes pads 122 on the top of the bottom package 125 that are coupled to a top package 105 by a top package to bottom package coupling 120 (e.g., solder balls). The solder balls that provide the top package to bottom package coupling 120 need to be sized to meet a clearance requirement between the bottom package 125 and the top package 105. Specifically, the top package 105 should not contact the die 110. The solder balls should also be positioned far enough apart from each other so that electrical shorts do not occur between adjacent solder balls. Therefore, as the clearance requirement increases, the pitch between the top package to bottom package coupling 120 also increases. As the pitch increases, the number of separate electrical connections provided by the top package to bottom package coupling 120 for a PoP structure decreases.
FIG. 1B illustrates a prior art overmolded bottom package 135 that uses Thru Mold Via Technology (TMV®) PoP package. Compared with the bottom package 125 of the PoP structure 100, the overmolded bottom package 135 is more expensive to construct. An integrated circuit die 160 may be mounted on top of the overmolded bottom package 135 using a flip-chip configuration so that solder balls provide a die to bottom package coupling 155. The overmolded bottom package 140 includes a bottom package coupling 140 (e.g., solder balls) to couple the overmolded bottom package 140 to a printed circuit board or other system substrate. The overmolded bottom package 135 also includes pads 132 that may be coupled to a top package (not shown) by solder balls 152.
The pads 132 and solder balls 152 are formed on the top surface of the overmolded bottom package 135 before molding compound 140 is deposited to cover the entire top surface of the overmolded bottom package 135. A typical size for one of the solder balls 152 is 200 microns in diameter. The molding compound 140 is deposited to cover the entire top surface of the overmolded bottom package 135 and then, laser-cut vias 142 are formed to expose the solder balls 152. As shown in FIG. 1B, the molding compound 140 covers the integrated circuit die 160.
FIG. 1C illustrates the prior art overmolded bottom package 135 of FIG. 1B within a prior art MTV PoP structure 165. The molding compound 140 is used to meet a clearance requirement between the overmolded bottom package 135 and a top package 175 within the TMV PoP Structure 165. The vias 142 that are formed in the molding compound 140 prevent the solder balls 152 from collapsing after the top package 175 is coupled to the overmolded bottom package 135 and causing electrical shorts between the solder balls 152. The top package 175 is electrically coupled to the overmolded bottom package 135 by top package to bottom package coupling 162 (e.g., solder balls). The top package 175 is surface mounted to the exposed solder balls 152 on the overmolded bottom package 135 to form the TMV PoP structure 165. After a hot air reflow process (e.g., a reflow process utilizing a reflow oven, an infrared heater, etc.) is applied to the TMV PoP structure 165, the solder balls comprising the top package to bottom package coupling 162 and the solder balls 152 combine to form pillars of conductive material coupled to each of the pads 132.
In contrast with the top package to bottom package coupling 120 of the PoP structure 100, the solder balls comprising the top package to bottom package coupling 162 may be smaller in size because the top package to bottom package coupling 162 need not be sized to meet the clearance requirement between the overmolded bottom package 135 and the top package 175 within the TMV PoP Structure 165. Therefore, the solder balls 152 may be smaller, allowing for a smaller pitch for a top package to bottom package coupling 162 and more separate electrical connections between the top package 175 and the overmolded bottom package 135. A typical size for one of the solder balls in the top package to bottom package coupling 162 is 200 microns in diameter. However, the number of processing steps is increased to produce the overmolded bottom package 135 compared with the bottom package 125. Specifically, additional processing steps are needed to provide the solder balls 152, the molding compound 140, and the laser-cut vias 142. Thus, there is a need for addressing these issues and/or other issues associated with the prior art.